Lean Body Mass Calculator
Calculate your muscle mass and body composition with scientific formulas
Enter your measurements to calculate lean body mass
How It Works
What is Lean Body Mass?
Lean Body Mass (LBM) represents the total weight of everything in your body except fat. This includes your muscles, bones, organs, water, and all other non-fat tissues. LBM is a crucial metric for understanding your body composition, as it helps distinguish between weight from muscle versus weight from fat.
Unlike body weight alone, LBM gives you a clearer picture of your metabolic health and fitness level. People with higher lean body mass typically have faster metabolisms and better overall health outcomes.
Calculation Methods
Our calculator uses three scientifically validated formulas to estimate your lean body mass:
Boer Formula (1984)
Widely considered one of the most accurate formulas for estimating lean body mass. It uses separate equations for males and females to account for biological differences in body composition.
Female: 0.252W + 0.473H - 48.3
(W = weight in kg, H = height in cm)
James Formula (1976)
An older but still reliable formula that provides good estimates for the general population. Particularly useful for clinical applications.
Female: 1.07W - 148(W/H)²
(W = weight in kg, H = height in cm)
Hume Formula (1966)
A classic formula that has stood the test of time. Known for consistency across different populations.
Female: 0.29569W + 0.41813H - 43.2933
(W = weight in kg, H = height in cm)
Understanding Your Results
The calculator provides results from all three formulas, along with an average. Here's how to interpret them:
- •Lean Body Mass: The total weight of non-fat tissue in your body (muscles, bones, organs, water)
- •Body Fat: Your total weight minus your lean body mass equals your fat mass
- •Body Fat Percentage: The proportion of your body weight that comes from fat tissue
Why Use Multiple Formulas?
Each formula was developed using different study populations and methodologies. By providing all three estimates plus an average, you get:
- •Range of Values: See the variation between different scientific approaches
- •Confidence: If all three formulas are similar, you can be more confident in the estimate
- •Better Accuracy: The average helps balance out individual formula biases
Practical Applications
Knowing your lean body mass is valuable for:
- •Fitness Planning: Track muscle gain and fat loss separately during training
- •Nutrition Goals: Calculate protein needs based on lean mass (typically 1.6-2.2g per kg of LBM for athletes)
- •Metabolic Rate: Lean tissue burns more calories than fat tissue, affecting your daily energy needs
- •Health Monitoring: Track changes in body composition over time, beyond just weight
Important Note: These formulas provide estimates based on statistical averages. For the most accurate body composition analysis, consider DEXA scans, bioelectrical impedance analysis (BIA), or hydrostatic weighing performed by healthcare professionals. Individual variations in bone density, hydration, and muscle distribution can affect accuracy.
More Calculator Tools
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Frequently Asked Questions
What is lean body mass and why is it important?
Lean body mass (LBM) is your total body weight minus fat mass - it includes muscle, bone, organs, and water. Knowing your LBM helps determine appropriate protein intake, set realistic fitness goals, track muscle preservation during weight loss, and calculate accurate metabolic rates.
How accurate is the Boer formula?
The Boer formula is widely used in medical settings and provides reasonable estimates for most people. However, it's an approximation - actual LBM can vary based on individual factors. For precise measurements, consider DEXA scans, bioelectrical impedance analysis, or hydrostatic weighing.
How can I increase my lean body mass?
Build muscle through resistance training (weightlifting, bodyweight exercises), eat adequate protein (0.7-1g per lb of body weight), get sufficient sleep, and maintain a modest calorie surplus if gaining muscle is your primary goal. Progress takes time - aim for 0.5-2 lbs of muscle gain per month for sustainable results.
What's the difference between LBM and muscle mass?
Lean body mass includes everything except fat: muscle, bones, organs, water, and connective tissue. Muscle mass is just skeletal muscle. LBM is typically about 50-60% muscle, 20% bone, and 20-30% organs and other tissues. You can't directly control LBM, but you can increase muscle mass through training.
Is my data saved or shared?
No! All calculations happen locally in your browser. We don't collect, store, or share any of your measurements. See our Privacy Policy for details.
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Disclaimer: This calculator provides estimates for informational purposes only. Results are approximate based on mathematical formulas and may not reflect precise body composition. For accurate body composition analysis, consult with healthcare professionals using DEXA scans or other medical-grade equipment. Not intended for medical diagnosis or treatment decisions.